My pediatrician gave me this formula to calculate how much baby should be drinking in 24 hours.
Upper limit: 200ml x baby's weight (KG)
Lower limit: 150ml x baby's weight (KG)
So if you're feeding between the upper limit and lower limit in a 24hr period, your baby is having enough to drink. For amt to feed at each feed, just divide by the number of feeds a day.
Other ways to judge if your baby is having enough is making sure that there're about 6-8 wet diapers a day as well as weight gain.